Protecting planted trees within woodland using mesh is usually more successful if you go wider rather than higher. However as long as you're trying to protect trees planted within woodland you could consider using the 6 foot (1.8m) tall tree planting tubes;
http://www.tubex.com/en/products/detail.asp?id=16
Do not use these if your trees are planted in the open - as they will not develop roots that will provide good support against the wind when their time being nursed is complete. (the architecture of tree roots develops in response to the swaying of the sapling in the wind - the 6foot tubes prevent the young tree moving sufficently in the wind to develop an appropriate root hold)
The long term problem though is that you can successfully protect your trees against deer but ultimately they will reach a size and stage when squirrels will be a problem - unless you're prepared to take sustained and intensive action. For reasons unkonwn and unexplained squirrels do seem to preferentially target planted trees. (hypotheses include different fungal associations on the roots of transplanted trees etc.)
Other things to think about when planting trees in woodland with deer problems are the relative palatability of trees and their differential abilities to recover from grazing.
For example Alder (which contrary to popular belief doesn't need wet conditions to grow you see it in wet places because in the wet it can outcompete other species)Alder is very unpalatable, and unless there is nothing else at all availsble to graze or browse alder is usually left untouched. Ash, Hazel and Oak are usually a favourite of deer and hard to protect, with beech and birch being somewhere inbetween.
Birch although often browsed by deer usually recovers better than other tree species- as long as the shade in which it's growing is not too dense. If you're planting in a shadier spot within your woodland then small leaved lime is very tolerant to being browsed and recovers very well even after sustained browsing year on year.
I would suggest getting some of the 6 foot tubes and including some alder in plantings within woodland - as long as the canopy isn't too dense.
The choice of species to plant in woodland is very complex. In my oppinion the NVC system usually used to choose what sort of trees are appropriate was developed by looking at woodland in britain - but in many ways ignores the impact of human management and use on the combinations of species present. The question of whether adding alder or small leaved lime into woodland is not a simple one - and to just quote that any given wood "should" be a particular kind of "standard" woodland and include only certain species is very involved and ultimately unresolved. Everything is changing climate change, diseases a massive increase in the number of deer. Woodland 'types', if they were ever anything other than a human construct, are certainly in a state of flux, and, I believe, should not be held as gospel.
Anyway I'm going off on a tangent!Ultimately your best bet will be to change your diet to one which is based on venison!